Black-throated Blue Warbler

The Black-throated Blue Warbler (Setophaga caerulescens) is a small, strikingly dimorphic songbird. Males are adorned with a black face and cheeks, deep blue upperparts, and pristine white underparts. Females, on the other hand, exhibit a more subdued olive-brown above and light yellow below. This species is known for its distinctive white wing patches, which may not always be visible.

Identification Tips

Adult males are unmistakable with their black throats and faces, contrasting with the deep blue of their upperparts and the white of their underparts. Females and immatures are less conspicuous; females have olive-brown upperparts and light yellow underparts with a gray crown and brown cheek patches. Both sexes have a thin, pointed bill and may show small white wing patches. Juveniles are brown above with a creamy eyebrow and spotted throat and underparts.

Habitat

The Black-throated Blue Warbler breeds in mature deciduous forests or mixed coniferous-deciduous forests with a dense understory, often in hilly or mountainous areas. During winter, it migrates to tropical wooded and scrub habitats in the Greater Antilles.

Distribution

This warbler breeds in the northeastern United States and southeastern Canada, migrating to the Caribbean for the winter months. It is occasionally recorded as a vagrant in western Europe.

Behaviour

Territorial in both breeding and wintering grounds, this warbler defends its space vigorously against conspecifics. It requires large, unbroken forest areas for nesting, and its numbers are sensitive to habitat fragmentation.

Song & Calls

The male's song is a buzzy "zee-zee-zeeee" with an upward inflection, while its call is a flat "ctuk."

Breeding

Monogamous and nesting close to the ground in thick shrubs, the Black-throated Blue Warbler's breeding season spans from May to July. Males attract females with soft melodies and follow them closely, engaging in displays of drooped wings and open bills.

Similar Species

The Black-throated Blue Warbler is similar to other warblers in size and shape but can be distinguished by its unique coloration and white wing patches.

Diet and Feeding

Insectivorous by nature, this warbler forages actively in low vegetation, supplementing its diet with berries and seeds in the winter. Males and females exhibit different foraging behaviors, with males typically foraging at higher levels.

Conservation Status

The IUCN lists the Black-throated Blue Warbler as Least Concern, with a population trend that is currently increasing. However, deforestation and habitat fragmentation, particularly in its tropical wintering areas, pose threats to its survival. Climate phenomena such as El Niño can also impact its survival and fecundity rates.